Nuummite is a rare metamorphic rock primarily composed of anthophyllite and gedrite amphiboles. It is highly prized by collectors for its distinctive iridescent flashes of gold, blue, or red, which are best visible when the material is polished.
Is this nuummite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch nuummite with a known reference. Nuummite sits at Mohs 5.5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nuummite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Nuummite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, dark gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive.
Often confused with
Nuummite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nuummite leaves white, Arfvedsonite leaves grey to bluish-grey; luster reads submetallic on Nuummite and vitreous on Arfvedsonite.
How to tell apart: Luster reads submetallic on Nuummite and vitreous on Anthophyllite.
How to tell apart: Streak differs — Nuummite leaves white, Hypersthene leaves greyish-white.
Often found alongside nuummite
Minerals reported to co-occur with nuummite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Fe)₇Si₈O₂₂(OH)₂
- Mohs hardness
- 5.5-6
- Density
- 3.1-3.3 g/cm³
- Streak
- White
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive
- Cleavage
- Perfect in Two Directions
- Rarity
- Uncommon
- Uses
- Lapidary, Ornamental, Collector
- Host rock
- Metamorphic Amphibolite Complex
- Typical price
- $20-200 per specimen
Where rockhounds find nuummite
Classic worldwide localities
- Nuuk, Greenland
Field-hunting tip
Look in metamorphic amphibolite complex country — that is the host setting where nuummite typically forms. If you start seeing gedrite, anthophyllite, pyrite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nuummite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
